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An ape scratching its nose

A new study led by experts from our Psychology Department has revealed that apes such as chimps and bonobos show striking similarities to humans in how they interact using signals.

The mutual awareness in signalling before and after an encounter had never previously been seen in any species other than humans, the researchers said, and suggests that apes seem to value some form of commitment in interaction with other apes.  

Signalling before and after social interaction

Our pioneering scientists studied 1,242 interactions between apes in four different zoos in France, Switzerland and USA, and found that apes use signals and look at each other before starting and ending social interactions, comparable to how we say hello and goodbye.

Typical signals used in the current study were gestures such as touching each other, holding hands, butting heads or gazing at each other.

Precisely which types of signals serve to enter and exit from interactions is currently still being analysed by the researchers in a follow-up study.

Researchers established that bonobos exchanged entry signals and mutual gazes 90% of the time and chimps 69% of the time. Exit signals were even more frequent, with 92% of bonobos and 86% of chimpanzees displaying signals to end interactions.  

Signs of social etiquette

Bonobos’ entry and exit phases also seem to resemble patterns of human politeness.

They exhibit more communication ‘efforts’ when interacting with a social partner that is less socially close to them.

These social protocols are much more relaxed when they interact with a friend, just like how we may communicate and interact informally with a friend.

Our experts believe this behaviour is influenced by complex social and power dynamics in the apes’ society, again similar to how we may interact based on our social hierarchies.

The researchers advocate for future studies investigating why bonobos behave this way.

Recent research using computerised tasks in captivity, as well as behavioural research on wild bonobos, has shown that bonobos, indeed behave friendly towards unknown conspecifics.  

Apes engage in ‘joint commitment’

Interestingly, the data on signalling exchanges prior to and after interactions suggest that apes seem to value some form of joint commitment.  

This is also supported by another past study of the same research team, which showed that bonobos use gestures and signals to resume a grooming activity they were previously occupied with, even when they were interrupted.

Joint action coordination (in entry and exit phases) has been long argued to be unique to humans only, which now has been observed among the great apes too.   

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